I Chose the 383 Big Block
IDK what your budget is but strongly consider hot tanking the block to clear out any gunk, new freeze plugs & reuse the threaded parts. I know you asked about a cam recommendation but what are your plans for the engine (daily driver, hot street, street/strip, strip, some of each, etc.)? I think you're limiting your cam choices if you intend to simply replace the #8 piston with another stock low compression cast piece. As others have said, your 383 would benefit from increased compression. If no one has monkeyed with your heads, they should be 906s which is a plus. When you clean them up, replace the valve stem seals. What intake & carb are you thinking about or are you going to reuse the cast iron 2 bbl? Lots of choices - you may need to temper your expectations depending which direction you go. You are doing the right thing by asking & answering questions. A big block in an A-body is a beautiful thing.